Accurate bag counter



March 19, 1963 A. H. PLACH Em. l 3,081,861

ACCURATE BAG COUNTER l JNVENTORS N ,4N/,v H. PMC/f I By Az v//v f. [maso/v March 19, 1963 A. H. PLACH ETAL 3,081,861

, ACCURATE BAG COUNTER Filed July 8, 1960 5 Sheets-Sheet 2 BY zfy,

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United States Patent() 3,081,861 ACCURATE BAG COUNTER Alvin H. Plach and Alvin E. Ericson, Chicago, Ill., as-

signors to Union Carbide Corporation, a corporation of New York Filed July 8, 1960, Ser. No. 41,606 7 Claims. (Cl. 198-40) This invention relates to apparatus for exact counting of plastic film units as for example, the counting of plastic bags as they are discharged from an automatic bag-making machine. More particularly, this invention relates to a device utilizing the electrical insulating property of the film comprising the unit bags as a control means to accurately count the bags as they are deposited on a pile by a ybag stacker. This invention additionally relates to means for signaling .the transfer of an accurate count of bags, from a stacking station to a collection station when a predetermined batch count has been registered. It is extremely diflicult to handle, count and stack bags of thermoplastic filmsuch as polyethylene or polyvinyl chloride film because such materials, being excellent electrical insulators, readily build up a charge of static electricity from -frictional contact, and by contact with and separation from other surfaces. The static charge on the film tends to cause the bags to stick to any surface with which they come in contact. Moreover, the limpness of the thin, unsupported lrn used for economical production of bags also interferes with handling, stacking and counting.v

Apparatus for stacking bags is usually provided with mechanical means for counting the cumulative number of mechanical cycles of the stacker unit. Such means are generally operated by a cam attached to the input drive of the stacker unit in such a way that it counts the cycles ofV` the stacker mechanism, regardless of the presence or absence of unit bags in gripper members which normally transport the finished bags from the bag-making machine to a stacking station. A batch counter connected to such indicating means will frequently shortcount such batches, since finished bags are not invariably delivered at each traverse of a gripper member of the Coasting of the machine upon startup and stopping, improper cutoff adjustment and gripper maladjustment are several reasons for such miscounts.

Consequently, a need exists for an accurate bag counter Which will ensure an exact count of stacked bags which is not attainable using the counting means furnished in the described bag-stacking assembly.

Accordingly, it is one object of this invention to provide an accurate bag counter for a bag stacking assembly.

Another object of this invention is to provide means for counting the exact number of units discharged from an automatic machine for making bags of thermoplastic film.

Another object is to provide means for signaling the transfer of an accurate count of bags, from a stacking station to 'a collection station when a predetermined batch count has been registered. v Y

Other and additional objects of this invention will become apparent hereinafter. f

According 'tothe present invention, an accurate bag counter is provided for use in combination with a bag stacking assembly having a member for preferably grippinga thermoplastic bag as it is discharged from a bag making machine and transporting it to a stackingstation where the bags are deposited in a pile'.V The accurate bag counter comprises in association with said gripper member an electrical circuit having a resistance greater than a predetermined resistance value when a bag is gripped by the gripping member at the stacking station and a lower resistance value when a bag is not gripped' by said gripping ice member. Resistance sensitive means are connected in the electrical circuit and in circuit relation with a counter, and wherein the resistance sensitive means causes said counter to register a count only when such electrical circuit has an electrical resistance greater than the predetermined electrical resistance value. Means associated with the bag stacking assembly connects the resistance sensitive means in circuit relation with the counter only when the gripping member is at the stacking station. Thus, before a count will be registered, the electrical circuit must have a resistance greater than the predetermined resistance v value, and the gripping member must be at the stacking station.

Conveying means are also provided for transporting a pile of bags from the stacking station to a collection station when a predetermined count of bags is reached. More particularly, when the counter reaches such count, it is connected in circuit relation with means which thereby actuate said conveying means.

The nature of the invention and the manner in which the invention may be practiced will become clear from the detailed description when taken in conjunction with the accompanying drawings forming a part of the specification and wherein:

FIG. 1 is a schematic elevation and fragmentary wiring diagram of a bag-making machine and bag-stacking assembly;

FIG. 2 is a fragmentary enlarged plan View of a gripper member of the bag-stacking assembly;

FIG. 3 is a transverse vertical section taken along line 3-3 of FIG. 2;

FIG. 4 is a transverse vertical section of an open gripper member taken along line 3 3 of FIG. 2; and

FIG. 5 is a schematic wiring diagram of the control circuits shown in FIG. 1 and fragmentaryperspective of the cam shaft and switches connected thereto.

Referring now to FIG. 1, bag-making machine 10 advances continuous tubular thermoplastic lm 2 intermittently to and through indicia, heat-sealing stations (not shown), to draw rolls 4 and severing knife 6, where it is cut into a unit bag 8. Unit bags 8 are discharged from the severing knife 6 of the bag-making machine 10 onto bag-delivery assembly 11, which presents the bags to bagstacking unit assembly 20. Bag-delivery assembly 11 comprises a plurality of round conveyor belts 12 driven by v pulleys 14, 15.

The bag assembly 20 is driven by a conventional machine drive, not shown, and includes gripper members 30, 30a attached intermediate two spaced parallel roller chains 16 only one of which is shown, the chains being driven continuously over pairs of sprockets 18, 18a, and synchronized to cooperate with the bag-making machine cutolf knife 6. VGripper members 30, 30a are each successively pivotally opened and closed to grip the trailing end of a unit bag `8, while it is being advanced and supported on the upper flight of the plurality of spaced round belts 12.

The gripper members 30, 30a grip the bagstrailing end and transport each bag 8 from'bag-delivery assembly 11` y Y 30,-730a of assembly 20 are each comprised of a gripper carriage bar 36 and coactingfnger bar 38. Finger bar l 38 is rotatably mounted and spring loa-ded so that a plurality of electrically conductive spaced fingers 40 affixed thereon are normally in pressing engagement with machine surface 42 of gripper carriage bar 36. The finger bar 38 is rotated to disengage fingers 40 from surface 42 at the loading and discharge stacking stations by an 4appropriate bar linkage (not shown) connected to chain 16, which linkage is actuated as thechain passes around sprockets 18, 18a.

As hereinbefore mentioned, the predetermined count was `formerly registered by mechanically counting the machine cycles, whether or not -unit bags were actually delivered to the pile, which of course, frequently resulted in an inaccurate bag count. However, the bag-counter of this invention, which is to be described presently in detail, actually detects the presence of a bag in the gripper member 30, or v30a at the stacking or advance station 26 before a unit of the count can be registered, and thereby furnishes an accurate bag count. Moreover, the bag counter of this invention detects the absence of a bag in the gripper fingers 40, regardless of the varying amounts of dirt or anti-blocking powder which may ha-ve been on the plastic film and deposited between the gripper fingers 40 and a sensing electrode 44 hereinafter described. It is to be noted that anti-blocking powder such as a chemically and physically treated mixture of 50% potato starch and 50% corn starch is customarily used in liberal quantities on the interior and exterior surfaces of thermoplastic bags, to prevent blocking of a pile of bags and to facilitate withdrawal of single bags by a customer.

One or a plurality of electrodes 44 interior to insulat ing sleeves 46 are vertically set into gripper carriage bar 36 and spaced s-o that electrode ends 48 electrically contact the upper surface of opposing electrically conductive gripping fingers 40 when there is no film intervening between ingers 40 and surface 42. When a film bag 8 is gripped between surface -42 and tingers 40 which are at ground potential (see tFIG. electrode 48 is thereby insul-ated lfrom the machine ground potential. Insulated electrodes 44 are electrically connected by collector wires 50, 51 to an electrically conductive rolling contac-t assembly aixed to one end of the gripper bar assembly and insulated therefrom. The contact assembly is comprised of an arm 54 rotatable around pivot pin 52, which has a contact roller 56 at the `free end. Pivot pin 152 is affixed to nger bar 38 by angle clips 53 insulated by pads 55.

An electrically conductive contact bar '58 electrically insulated from the stacker frame is positioned in line with contact roller 56 near bag-stackingstation 26. Bar 58 is electrically connected to an electronic resistance sensi- 'tive relay 60, such as General Electrics CR7511A126GI electronic relay. Resistance of the circuit from relay 60 to contact bar 58 is high because it is insulated from ground.' Referring to FIG. 5, the resistance sensitive relay 60 is a magnetic relay, controlled by an electron tube amplifier. It is comprised of normally closed contacts 61, and actuating circuit means 63 connected in circuit relation with contact Abar 58 and ground through a coaxial cable 65. The relay actuating circuit means 63 includes an electron tube amplifier 67 which can be regulated to respond to a change in resistance in an external circuit,

such as the combination of contact bar 58 and roller 56, electrode end 48, gripper finger 40, and ground to open the normally closed contacts 61. One side of contacts 61 is connected in circuit relation with a cam actuated switch ener-gizes counter 66 when the external resistance increases above a reference value of resistance preset with the potentiometer, suclras 5 megohms (5,000,000 ohms). It is to be lnoted that a direct contact sensing device is not suitable 1n the accurate counting application on a bag machine handling thermoplastic bags, because the antiablocking powder generally -used on the bags in liberal quantities, gets into'electrical contacts, thereby insulating the contact points and thus creating a resistance which may vary from l1000 ohms to 10,000 ohms. The insulation provided by a thermoplastic bag between the same electrical contacts is of the order of 500 megohms (500,000,000 ohms).

When either gripper assembly 30 or 30a is advanced to stacking station 26, roller 56 engages insulated contact bar 58 thereby electrically connecting electrode end 48 to the actuating circuit means 63 of relay 60. When a bag is held in either gripper 30 or 30a, thereby insulating electrode end 48 from ground which is connected to gripping nger 40, resistance at the input of relay 60 remains high, such as in the order of 500 megohms, even when gripper contact roller 56 engages insulated contact bar 58; and the normally closed relay contacts 61 are not operated. Thus, each revolution of counter cam 64, arranged to coin cide with the traverse of each gripper bar 30, 30a, actuates switch 62 which registers a bag count on counter 66.

When no bag is held in gripper 30, 30a, as it traverses insulated contact bar 58, electrode 44 is short-circuited to gripping finger 40 which is at ground potential. Resistance at input of relay 60` becomes very low, such as up to about 10,000 ohms and the normally closed contacts 61 open, thereby opening the circuit to counter 66 and no count is registered. Counter 66 is a unit, such as Acratrol Series C-35-3, Count Selector and Controller made by Counter and Control Corporation. The Acratrol counter is a solenoid-operated ratchet device. Each pulse of current from relay 60 actuates the solenoid to move the ratchet wheel one tooth, thereby operating the cam connected to the ratchet on a common shaft. In the commercial device, there is a change gear arrangement interposed between the ratchet and cam :and adjustable so that the cam may turn one revolution for either of 25 or 50 or 100 or 200'pulses fed to the counter. Thus, the traverse of each bag in a gripper assembly registers a count on counter 66.

Referring now to means for advancing a predetermined count of a pile of bags from stacking station 26 to collection station 28, one side of normally open cam actuated contacts 69 in the counter 66 is connected in circuit relation with an electrically operated clutch 68 and one side of a v. D.C. source. The other side of the cont-acts 69 is in circuit relation with a cam actuated switch 70 and the other side of said 90 v. D.C. source.

When the predetermined count for a pile of bags has been registered, counter 66 closes normally open contacts 69 for that portion of the machine cycle determined by transport cam 72 actuating switch 70. Transport cam 72 is adjustable to control the length of travel of Ibelt 32.

The closed contacts in counter 66 and switch 70 actuate electrically operated clutch 68 to engage belt 32 with the` 1. =In combination with a bag stacking assembly having a member for gripping a thermoplastic bag tat one station and transporting it to and depositing it `at a stacking sta tion,.means ffor counting the bags comprising yan elec` trical circuit associated with said gripper member', said circuit having a resistance greater than a predetermined resistance when a ba-g is gripped by said grippingmember at the stacking station and a different resistance when a `bag is not gripped by said gripping member :at the stacking station, a counter, and resistance sensitive means in circuit relation with lsaid electrical circuit and adapted toY cause said counter to register .a count when said electrical circuit has a resistance greater than said predetermined resistance.

2. In combination with a bag stacking assembly having a member for gripping a thermoplastic bag at one station and transporting it to and depositing it at a stacking station, means for counting the bags comprising lan electrical circuit associated with said gripper member, said circuit having a resistance greater than a predetermined resistance when `a bag is gripped 'by said gripping member at the stacking station and a dilerent resistance when a bag is not gripped by said gripping member at the stacking station, a counter, and resistance sensitive means in circuit relation with said electrical circuit and adapted to cause said counter to register a count ywhen said electrical -circuit has a resistance greater than said predetermined resistance, and means associated with said bag stacking -assembly for connecting said counter in circuit relation with said resistance sensitive means when the gripper member is at the stacking station.

3. In combination with ra bag stacking assembly having a member for gripping la thermoplastic bag at one station and transporting it to and depositing it at a stacking station, means for counting bags comprising an electrical circuit associated with said gripper member having a relatively high electrioal resistance when Ia bag is gripped by said gripping member at the stacking station and a lower electrical resistance when a bag is not gripped by said gripping member at the stacking station, a counter, resistance sensitive means in circuit relation with said electrical circuit and adapted to cause said counter to register a count when Isaid electrical circuit is at said high electrical resistance, means for connecting said resistance sensitive means in circuit relation with said counter, and means associated with the lbag stacking Vassembly for actuating said'connecting means when the gripping member is at the stacking station.

4. In combination with a bag stacking assembly having a member for gripping a thermoplastic bag at one station and transporting it to and depositing it at -a stacking station, means for counting bags comprising an electrical circuit associated with lsaid gripper member havingra relatively high resistance when a :bag is gripped by said gripping member at the stacking station and 1a lower electrical resistance when a bag is not gripped by said gripping member at the stacking station, a counter, resistance sensitive means in circuit relation with said electrical circuit Iand adapted to cause said counter to register a count when said electrical circuit is `at said iirst resist-ance, a normally open switch adapted to connect said lresistance sensitive means in circuit relation with said counter, and means associated with the bag stacking assembly for closing said switch when the gripping member is at the stacking station.

5. In combination with a bag ystacking assembly having a gripper including a member and a coacting finger between which a bag is gripped at one station and transported to and released at a stacking station and wherein said member and coacting linger are adapted to contact one another when no bag is held therebetween atV said stacking station, means @for counting bags comprising a fixed contact lbar at the stacking station normally insulated from ground, an electrode normally insulated from ground in said member and adapted to contact said coacting inger when no bag is gripped therebetween, means vfor connecting said electrodein circuit relation with said contact bar when the gripper member is at the stacking station, means for connecting said gripper coacting linger in circuit relation with ground, said contact bar and electrode thereby being insulated from ground when a bag is gripped between said member and coacting ringer at the stacking station and being at ground when no bag is held therebetween at the stacking station because of the contact between said electrode a-nd coacting finger, a counter resistance sensitive means in circuit relation with said contact bar and ground and adapted to cause said counter `to register a count only when said contact bar is insulated from ground, and means associated with said bag stacking assembly for connecting said counter in circuit relation with said resistance sensitive means when the gripper is at the stacking station.

6. In combination with a bag stacking assembly having a member for gripping a thermoplastic bag at one station and transporting it to and depositing at a stacking station, means for counting comprising an electrical circuit associated with said gripper member, said circuit having a resistance greater than a predetermined resistance when a bag is gripped by said gripping member at the stacking station and a diierent resistance when a bag is not gripped by said gripping member at the stacking station, a counter, resistance sensitive means in circuit relation with said electrical circuit and adapted to cause said counter to register a count when `said electrical circuit has a resistance greater than said predetermined resistance, means associated ywith said bag stacking assembly for connecting said counter in circuit relation with said resistance sensitive means when the gripper member is at the stacking station, means for transporting a pile of bags from the stacking station to a collection station, and means for connecting the counter in circuit relation with said transporting means, said counter adapted to actuate said moving means when a predetermined count of bags is reached.

7. In combination with a bag stacking assembly having a member for gripping a thermoplastic bag at one station and transporting it to and depositing at a stacking station, means for counting comprising an electrical circuit associated with said gripper member, said circuit having a resistance greater than a predetermined resistance when a bag is gripped by said gripping member at the stacking station and a different resistance when a bag is not gripped by said gripping member at the stacking station, a counter, resistance sensitive means in circuit relation with said electrical circuit and adapted to cause said counter to register a count when said electrical circuit has a resistance greater than said predetermined resistance, means associated with said bag stacking assembly for connecting said counter in circuit relation with said resistance sensitive means when the gripper member is at the stacking station, means for transporting a pile of bags from the stacking station to a collection station, a normally open switch adapted to connect said counter in circuit relation with said moving means; and means associated Iwith the `bag stacking assembly for closing said switch when the gripping member is at the stacking station, said counter adapted to actuate said transporting means when a predetermined count of bags is reached.

References Cited in the le of this patent UNITED STATES PATENTS 2,731,204 Darling Ian. 17, 1956 

6. IN COMBINATION WITH A BAG STACKING ASSEMBLY HAVING A MEMBER FOR GRIPPING A THERMOPLASTIC BAG AT ONE STATION AND TRANSPORTING IT TO AND DEPOSITING AT A STACKING STATION, MEANS FOR COUNTING COMPRISING AN ELECTRICAL CIRCUIT ASSOCIATED WITH SAID GRIPPER MEMBER, SAID CIRCUIT HAVING A RESISTANCE GREATER THAN A PREDETERMINED RESISTANCE WHEN A BAG IS GRIPPED BY SAID GRIPPING MEMBER AT THE STACKING STATION AND A DIFFERENT RESISTANCE WHEN A BAG IS NOT GRIPPED BY SAID GRIPPING MEMBER AT THE STACKING STATION, A COUNTER, RESISTANCE SENSITIVE MEANS IN CIRCUIT RELATION WITH SAID ELECTRICAL CIRCUIT AND ADAPTED TO CAUSE SAID COUNTER TO REGISTER A COUNT WHEN SAID ELECTRICAL CIRCUIT HAS A RESISTANCE GREATER THAN SAID PREDETERMINED RESISTANCE, MEANS ASSOCIATED WITH SAID BAG STACKING ASSEMBLY FOR CONNECTING SAID COUNTER IN CIRCUIT RELATION WITH SAID RESISTANCE SENSITIVE MEANS WHEN THE GRIPPER MEMBER IS AT THE STACKING STATION, MEANS FOR TRANSPORTING A PILE OF BAGS FROM THE STACKING STATION TO A COLLECTION STATION, AND MEANS FOR CONNECTING THE COUNTER IN CIRCUIT RELATION WITH SAID TRANSPORTING MEANS, SAID COUNTER ADAPTED TO ACTUATE SAID MOVING MEANS WHEN A PREDETERMINED COUNT OF BAGS IS REACHED. 